Isaac yearsley



l. YEARSLEY, 1r.

M'i'llstnne-Dress for Bone-Nilis.

N0.147,733. PatenxeuFehJLmM..

UNITED STATES PATENT QFFICE.

isAAo rEAnsLnnon., or ooArnsvrLLn, rrsnsrLvArrA.

IMPROVEMENT IN MlLLSTNE-DRESS FR BONENHLLS.

Specification forming part of Letters Patent No. 147,733, dated February17, 1874; application filed May 21,1873.

To all whom it may concern:

Be it known that I, IsAAc YnAnsLnv, Jr., of Goatesville, Chester county,Pennsylvania, have invented an Improved Dress for Bone- Mills, of whichthe following is a specification:

The object of my invention is the eiiective trituration of bones bygrinding-surfaces which do not become unduly heated, and which can beused for a longer period than ordinary grinding-surfaces without beingimpaired, a-nd can be easily renewed by reversing the motion of themill. I attain this object by annular' grinding plates, portions ofwhich are shown in Figures l and 2 of the accompanying drawing, the saidplates having a dress consisting of annular rows of quadrangular teeth aa, the t'ull size of which is represented iu the perspective view, Fig.

The two grinding surfaces, Figs. l and 2, bear such relation to eachother that the annular rows of teeth ot' the revolving plate A shalltraverse the spaces between the annular rows of teeth of the fixed plateA', hence, supposing the view, Fig. 3, to represent a portion of thefixed plate, and the revolving' plate to be moving in the direction ofthe arrow, the cutting effect on the bones will be produced bythe actionof two ot' the four edges ot' each pyramidal tooth of the revolvingplate, in conjunction with two edges, w of each p yramidal tooth of thefixed plate. Vhen these cuttingedges of the teeth have become worn andunservicea-ble, the motion of the revolving plate should be reversed,when a new sharp set of cutting-edges are brought into play, hence theimportance of making the teeth of quadrangular shape, so as to presentfour cuttingedges. In order to permit this reversal of the motion of therevolving plate and still retain the triturating effect, it is essentialthat there should be groups of rows of teeth, the rows being parallelwith each other and with a radial line passing through the center ofeach group. Thus the plate A has a series of groups, m, of five rows ineach group, the

central row of which is on the radial line y y, the other rows beingparallel with the radial row, and all the teeth of each group being ofthe same size.

An gular vacancies necessarily occur between the groups m, and thesevacancies are studded with such teeth as the spaces will permit. Thedress of the plate A, Fig. l, varies slightly from that above described,but the same rule is observed as regards groups of parallel rows ot'teeth, and intervening angular spaces with teeth arranged in accordancewith the character of these spaces.

It will be observed that in each plate some of the teeth are removednear the inner edge, thus affording vacant spaces for admitting be tweenthe grinding-surfaces the particles of bones passing lfrom thepreparatory breaking portion of the mill, for it should be understoodthat the grinding-plates A and A represent the pulverizin g portion onlyof the mill.

I prefer to make each of the plates A and A with teeth on both sides, sothat when the teeth on one side have become defective the plates may bereversed, thereby presenting new and serviceable grinding-surfaces.

Practical tests have proved that mills with. the abovedescribed dressare free from that undue heating which is a formidable defect inordinary bone-mills.

I claim as my invention- The within described annular grinding plates,each having a dress composed of pyramidal teeth arranged in groups ofrows, which are parallel with a radial line passing through the centeroi' the group, as herein, set forth.

In testimony whereof I have signed my name to this speciiication in thepresenceof two subscribin g witnesses.

ISAAC YEAR-SLEY, JR.

Titnesses IsAAo YEARsLnY, WILLIAM YEARsLnv.

